1. Field of the Invention
The present invention relates to a radiation image pick-up device, and particularly to a radiation image pick-up device which can be suitably used for an X-ray image pick-up device for image pick-up of a human body by X-ray irradiation.
2. Related Background Art
Conventionally, there is an X-ray sensor having a structure in which a phosphor for converting an incident X-ray into light and a photosensor for detecting the light from the phosphor are laminated. A large number of photosensors such as a photosensor using a PIN type diode and a photosensor using an MIS type sensor as disclosed in U.S. Pat. No. 6,075,256 and the like are proposed and actually commercialized.
Currently, there are various needs such as high definition image taking and moving image taking. In order to satisfy these needs, it is required that X-ray detection efficiency, light utilization efficiency, a yield, high speed operation, a signal to noise ratio, and the like be further improved.
The present invention has been made in view of the above problems, and an object of the present invention is therefore to provide a radiation image pick-up device with a large size, in which detection efficiency, light utilization efficiency, and a yield can be improved, high speed operation can be realized, and a signal to noise ratio is improved, as compared with a conventional used device.
According to the present invention, a radiation image pick-up device for performing image pick-up by using radiation includes:
a plurality of input pixels, each having a wavelength converter for converting incident radiation into light, conversion means for converting the incident radiation and the light converted by the wavelength converter into charge, charge storage means for storing the converted charge, and read means for reading a signal corresponding to the charge stored in the charge storage means, and
a plurality of output lines for outputting charges read from the input pixels, which are connected with the plurality of input pixels.
Since both the wavelength conversion means (phosphor) and the charge conversion means (semiconductor detector) are used, the detection efficiency can be increased.
Also, the radiation image pick-up device further includes a first reset means for resetting the charge in the charge storage means.
Also, the plurality of input pixels, the output lines, and the first reset means are formed respectively on an insulating substrate, the first reset means includes a thin film transistor, and each of the input pixels includes a read thin film transistor.
Also, the reset thin film transistor and the read thin film transistor are made of non-single crystalline semiconductor.
Also, the radiation image pick-up device further includes a transparent electrode which is located between the wavelength conversion means and the charge conversion means and transmits the light converted by the wavelength conversion means.
Also, the charge conversion means has a semiconductor substrate for converting radiation into charge and a plurality of divided electrodes provided in correspondence with the plurality of input pixels formed on an insulating substrate, the semiconductor substrate and the insulating substrate are laminated, and the plurality of dividing electrodes and storage capacitors of the plurality of pixels are electrically connected with each other.
Also, the radiation image pick-up device further includes amplifiers for signal amplification in the output lines.
Also, the charge conversion means is formed on a semiconductor substrate and has a pn junction portion.
Also, the charge conversion means has an energy band gap with a band gap of at least 1 eV or larger.
Also, the radiation image pick-up device further includes a second reset means for resetting the output lines, which is connected with the output lines.
Also, the read means is composed of a thin film transistor made of non-single crystalline semiconductor.
Also, the charge storage means and the read means are formed on an insulating substrate in the same layer structure having a lower electrode, a dielectric film, a high resistance semiconductor layer, a low resistance semiconductor layer, and an upper electrode.
Also, the charge conversion means is made of semi-insulating semiconductor.
Also, the wavelength conversion means includes a phosphor.
Also, the radiation image pick-up device further includes a reflective layer in a radiation incident side of the wavelength conversion means.
Also, a thickness of a high concentration impurity region composing the charge conversion means is set to be ⅕ of an absorption ratio or less.
The details will be described in embodiment modes of the present invention.